Process for photopolymerization with carbonylated polynuclear sulfonyl chloride sensitizers

ABSTRACT

U.V. POLYMERIZATION OF A PHOTOPOLYMERIZABLE VEHICLE IS IMPROVED BY INCORPORATING INTO THE VEHICLE ABOUT 0.5%% BY WEIGHT OF A CARBONYLATED POLYNUCLEAR SULFONYL CHLORIDE.

3,827,960 PROCESS FOR PHOTOPOLYMERIZATION WITH CARBONYLATED POLYNUCLEARSULFONYL CHLORIDE SENSITIZERS Vincent Daniel McGinniss, MiddleburghHeights, Ohio, assignor to SCM Corporation, Cleveland, Ohio No Drawing.Filed Jan, 12, 1973, Ser. No. 323,086 Int. Cl. C08d 1/00; C08f 1/16 U.S.Cl. 204-15914 7 Claims ABSTRACT OF THE DISCLOSURE U.V. polymerization ofa photopolymerizable vehicle is improved by incorporating into thevehicle about 0.5- by weight of a carbonylated polynuclear sulfonyl Ichloride.

CROSS-REFERENCE TO RELATED APPLICATION The present patent application isrelated to my copending patent application bearing the identical title,and having the identical filing date, i.e., Jan. 12, 1973, andidentified with Ser. No. 323,032.

BACKGROUND OF THE INVENTION This invention relates to an improvement inprocess for polymerizing (curing) a photopolymerizable vehicle byexposure of same to U.V. radiation. Curing herein connotespolymerization and hardening to obtain a product that is practical forordinary use and normally is tackfree.

The vehicle used herein is the binder for a film in the nature of apaint, varnish, enamel, lacquer, stain, filler or ink. The polymerizedproduct can be a clear one, optionally tinted, or an opaque one, both ina variety of colors for the purpose of protecting, decorating, and/orapplying a message on a substrate. For convenience herein the bindingvehicle alone for polymerization and such vehicle compounded with otheringredients Will be referred to from time to time herein as a paint.This paint can be a fluent, liquid phase-continuous material or apowdery mixture. It can have, if desired, opacifying pigment, addedcolorants and fillers, in conjunction with such binding vehicle. Suchpaint also can have various other conventional additives such aspesticides, odorants, flow-control agents, bubble breakers, defoamers,plasticizers, intercoat adhesion-promoters, and other ingredientsconventional in surface coating films.

Conventional convection ovens and infrared sources have been used tocure (polymerize) binders in surface coating or decorating films andinks, often with the assistance of a catalyst in such deposit. Morerecently ultraviolet (U.V.) wave energy curing of such binders(vehicles) has been suggested using suitable U.V. sensitizers forinitiating photopolymerization at wave lengths in the U.V. spectrum thatare transmittable through a quartz or other transparent window,generally such range understood as lying between about 1600 A. and about4000 A.

Typical U.V. emitters for such curing include ones such as the plasmaarc torch described in U.S. Pat. 3,3 64,3 87, various electric arclamps, and even lasers having a lasing output in the U.V. spectrum range(as shown in the copending U.S. patent application of De Souza andBuhoveckey, U.S. Ser. No. 189,254). The subject matter of thatapplication and U.S. Pat. 3,364,387 are incorporated herein byreference.

Advantages of the instant invention over prior proposals includeespecially economical and efiicient utilization of U.V. energy,particularly that in wave lengths between about 3200 A. and 4000 A. toperform cold polymerization (curing) of the vehicle at quite high speedwith attendant suppression of losses due to volatilization United StatesPatent 0" Patented Aug. 6, 1974 of components of paint,"suppression ofdiscoloration or degradation of the resulting deposit (which can begenerally considered a film) and avoidance of shrinkage and distortion(the preservation of dimensional stability) and suppression ofdegradation of the substrate to which the vehicle deposited is applied,particularly when such substrate is a plastic, or paper, or fabric.

SUMMARY OF THE INVENTION wherein R represents hydrogen, alkyl (Ca-haloalkyl (C phenyl and substituted phenyl wherein the substituent isalkyl, alkoxy, a-haloalkyl or chlorosulfonyl, polynuclear aromaticradical; and R and R represent one or more fused ring, alkyl (C anda-haloalkyl; and n is a number of at least 1.

Typical sulfonyl chloride compounds are:

l-Chloromethyl, 6-chlorosulfonyl naphthyl-Z, phenyl ketone.

6-Chlorosulfonyl naphthyl-l, phenyl ketone.

8-chloromethyl S-Chlorosulfonyl,

naphthyl-2, phenyl ketone.

CHzCl SOzCl l-Chlorosulfonyl anthracyl-9, phenyl ketone.

Z-Chloiosulfonyl anthracyl-9-,- phenyl ketone.

6-chlorosulfonyl l-chlororneth'yl,

naphthyl-Z, hexyl ketone.

moor o S-Chlorosulfonyl, naphthyl-2, a-bromopentyl ketone.

S0201 4-methoxy, S-chlorosulfonyl naphthyl-Z, methyl ketone.

O iil--CH clots ot'zm 6-Chlorosulfonyl phenanthryl-Z phenyl ketone.

7-Chlorosulfonyl phenanthryl-Z phenyl ketone.

8-Chlorosulfonyl phenanthryl-Z phenyl ketone.

Z-Chlorosulfonyl phenanthryl-3 phenyl ketone.

6-Chlorosulfonyl phenanthryl-3 phenyl ketone.

8-Chlorosulfonyl phenanthryl-3 phenyl ketone.

3-Chlorosulfonyl, S-benzoyl acenaphthene.

SOrCl Monochlorosulfonation of such compounds appears adequate, and thusis preferred for efficiency and econo'rny. There appears to be noparticular significance attributed to the position of the sulfonylchloride radical in relation to the carbonyl group. The essentialfeature is that the sul-fonyl chloride be substituted on the aromaticmoiety.

A convenient way to prepare such sulfonyl chloride materials is to reactthe carbonylated naphthyl compound or its substituted derivatives withchlorosulfonic acid in excess of the stoichiornetric amount needed forthe particular extent of chlorosulfonation desired, heating to about C.for an hour (or even more drastic where plural chlorosulfonation isdesired), pouring the reaction product on ice, then separating theorganic material from the resulting aqueous layer. Normally solidsulfonyl chloride products are most easily filtered oil, and normallyliquid ones decanted, but other conventional separation techniques canbe used where necessary or desirable.

Frequently the needed proportion of instant su'lfonyl chloridesensitizer also can be incorporated directly into the vehicle as a unitof a further polymerizable monomer, oligo'mer, prepolymer, or polymervehicle. In such instance, for example, the sulfonyl chloride compoundhas a reactable functional group on it such as a carboxyl group or anhydroxyl group. Typically, then, such sulfonyl chloride compound can bemade to react with a further polymerizable material, e.g., glycidylacrylate, either in monomeric form or already part of a preformedprepolymer or oligomer.

Typically the vehicles can constitute the entire deposit or a binder forsolids to yield a cured product in the nature of a paint, varnish,enamel, lacquer, stain, or ink. Usually the vehicles are fluid atordinary operation temperature (between about 30 F. and about 300 F. andadvantageously between ordinary room temperature and about 180 F), andwhen polymerized by the UV. radiation, give a tack-free film or depositthat is durable enough for ordinary handling. In the cured state suchvehicle is resinous or polymeric in nature, usually cross-linked.Uncured for application to a substrate or uncured on such substrate,such vehicle consists essentially of a monomer or mixture of monomers,or a further polymerizable oligomer, prepolymer, resin, or mixture ofsame, or a resinous material dispersed or dissolved in'a solvent that iscopolymerizable therewith. Such solvent ordinarily is monomeric, but canbe an oligomer (i.e., up to 4 monomer units connected) or prepolymer(mol weight rarely above about 2000). Oligomers and prepolymers shouldbe understood herein as being polymeric in nature.

In the main such vehicles or binders are those which also areconventionally polymeriza'ble by free radicalinduced additionpolymerization using peroxy or azo catalysis or .a redox system.Alternatively, however, the "binders can be a fluent material whereinthe ultraviolet wave energy causes photochemical generation of acatalytic material or effects a rearrangement which starts apolymerization that continues until a usefuly polymerized depositresults. The useful vehicles can be polymeric, monomeric, or a mixture,especially those exhibiting polymeric, monomeric, or a mixture,especially those exhibiting polymerizable vinyl, acrylic, allylic,mercaptan, fumaric, .maleic, or like unsaturated functionality.lReactive polymeric types include unstaturated polyesters, acrylics,epoxies, urcthanes, and siliconcs. Representative polymeric 'vehiclesinclude those derived from the reaction of dibasic acids or theiranhydrides with polyols. 'For example, equimolar amounts of maleicanhydride and phthalic anhydride can be reacted with propylene glycol inslight excess to form an unsaturated polyester which can be extendedwith styrene to a pre-selected value of nonvolatiles (n.v.), generallybetween 50 and 80% n.v. The polyester resin thus prepared should have anacid number of about 60 and less. Of course, fumaric acid can besubstituted easily for the maleic anhydride. Similarly, propylene oxidecan be substituted for the major portion of propylene glycol. Alsoinstead of styrene other active monomers such as hydroxyethyl-acrylatecan be used, usually up to about 50% by weight.

As to acrylic and other polymers, they are trimethylolpropanetriacrylate, pentaerythritol triacrylate, ethyleneglycol diacrylate,diacrylic acid adduct of the diglycidyl ether of bisphenol A (DER 332diacrylate) a dior triisocyanate reacted with a hydroxy containingacryla'te such as hydroxyethyl or hydroxypropyl acrylate.

Reactive monomer types include a variety of acrylates such ashydroxyethyl, cyclohexyl, hydroxypropyl, 2-ethylhexyl, benzyl,phenoxyethoxy, lower alkoxyethoxy, tetrahydrofurfuryl, similaracrylates, and also N-vinyl pyrrolidone, vinyl acetate, vinylacetate-butyrate, styrene and substiuted styrenes.

The instant sulfonyl chloride sensitizers are useful by themselves or inadmixture with other sensitizers that are conventional such as benzoin,benzoin ethers, oxime ethers, and phosphines. Additionally, to enhancecure throughout the vehicle when the vehicle temperature issubstantially above about 100 F. and such vehicle is particularlysusceptible to such catalysis, a minute pro portion of a peroxy or likefree-radical catalyst can be used.

Not only is the speed of U.V. curing quite good using the presentsulfonyl chloride sensitizers, but also the depth of cure is quitepractical so that the resultant polymerized deposit resists scratchingor disruption when first ostensibly dry on the surface. Curing cancontinue on stored pieces. Typical film thickness for the deposit can beabout 0.1 to as high as mils or even substantially higher, e.g., 30-50mils. Preferred cured deposits are continuous films, but decorative ormessage-transmitting ones need not be.

Typically the substrate workpieces coated with the uncured deposit ordeposits are passed under a U.V.- providing light beam by a conveyor.The substrate being coated can be metal, mineral, glass, wood, paperplastic, fabric, ceramic, etc.

Many useful pigments can be incorporated, in modest proportions,'intothe vehicle Without much deleterious effects. Thus, opacifying pigmentssuch as Zinc oxide can be used quite well. Titania, e.g., anatase andparticularly rutile, makes for a such more difiicult film to cure byU.V. radiation, but such opacifying pigmentation can be used. Otherfiller materials and coloring pigments such as basic lead sulfate,magnesium silicate, silica, clays,

wollastonite, talcs, mica, chromates, iron pigments, Wood flour,microballoons, hard polymer particles, and even reinforcing glass fiberor fiake also are suitable in the vehicle to make a paint. Ordinarily itis most desirable to use 'pigmen'ts which do not absorb a great deal ofU.V. wavelength in the same region of the U.V. spectrum as is absorbedby the instant sulfonyl chloride sensitizers. However, by use of adjunctenergy-transferring, U.V.-sensitizing materials such as Michlers ketonein the sensitizing mixture, sufficient energy transfer often can beobtained to activate the instant sulfonyl chlorides and enhance thecuring of pigmented systems. The wave length of U.V. should not, be toosimilar to or close to the wave length absorbed by the pigment in theU.V. range for best advantage of the irradiation process. Pigmented orfilled films for the process preferably are no more than about mil thickand'generally about 0.1-0.5 mil thick, maximum, for efficiencyandeconomy of curing.

Where it is desirable to induce fusion or flow in a 'wet '(uncured)paint deposit such as a powder, followed by a polymerizing cure of thetype available by use of the instant improvement, it can be advantageousto first Warm the deposit or substrate by a conventional method; e.g.,forced or natural convection, electrical induction or with a source ofinfrared energy, then follow this with the U.V. radiation for cure.

The following examples show ways in which this invention has beenpracticed, but should not be construed as limiting it. Unless otherwisespecifically stated herein, all parts are parts by weight, allpercentages are weight percentages, and all temperatures are in degreesFahrenheit. Where the binder being cured is of the type normally curableby free-radical polymerization, it is sometimes advantageous forcompleteness of cure and a speed to maintain a substantialy inertatmosphere above the irradiated workpiece; e.g., by a purge of nitrogenor other inert gas, but this is not required in all situations.

EXAMPLE 1 A clear coating of /3 part phenyl cellusolve acrylate, /3 partethylene glycol diacrylate, and /3 part of trimethylolpropanetriacrylate is prepared as the vehicle for test curing using a plasmaarc radiation unit.

The curing apparatus is an intense radiation torch (plasma arc)optically directed by a reflector system to irradiate a freshly paintedflat aluminum workpiece pass ing below a rectangular irradiating windowon an en closed horizontal conveyor moving at various line speeds(providing about 0.2 second of irradiation at feet a minute and 0.1second of irradiation at 200 feet a minute). The atmosphere around theworkpiece during its irradiation is kept essentially inert by purging itwith nitrogen. Radiation energy supplied by such apparatus at theworkpiece surface is about 35 kilowatts per square foot with slightlyless than about 6 kilowatts per square foot thereof being in the U.V.spectrum. Such sort of torch is described in US Pat. 3,464,387.

The above clear coating is applied to the aluminum workpiece (panel) asa film of about 0.4 mil thickness utilizing a wound wire rod #8. Thecoated panel is subjected to the radiation emitted by the apparatusdescribed but the film does not cure completely even when exposure atline speed of 100 feet per minute is continued for times (total actualexposure time is 30 seconds). Incomplete cure of the film is recognizedby being tacky to the touch.

The vehicle is dosed with 2% by weight ofl-chloromethyl,6-chlorosulfonyl naphthyl-2 phenyl ketone well mixed in.The sensitized coating is spread at about 0.4 mil thick on the aluminumtest panel and is cured at room temperature by subjecting it to theapparatus as above described. At line speeds of 100 and 200 feet perminute the vehicle cures tack-free and has a good scratch resistance tothe fingernail, indicating good cure throughout the film depth.

EXAMPLE 2 In this operation the same apparatus, operation, and vehicleof Example 1 are used, except that 1% of thel-Chloromethyl,6-Chlorosulfonyl naphthyl-2 phenyl ketone is used. Theresults are substantially the same.

EXAMPLE 3 In this operation the same apparatus, operation, and vehicleof Example 1 are used, except that 2% 4-methoxy,5- Chlorosulfonylnaphthyl-2 methyl ketone is used. The results are approximately the sameas Example 1, even the amount of the sensitizer is reduced to 1% byWeight.

EXAMPLE 4 In this example, the same apparatus, operation, and vehicle ofExample 3 are used including the sensitizer WhlCh is combined with 0.3%of Michlers ketone. The

results are substantially the same as in the preceding examples.

EXAMPLE Similar to Example 4 a 2% mixture comprising 1.7% offi-chlorosulfonyl phenanthryl-9 phenyl ketone and 0.3% Michler ketone isused. The results show identical curing characteristics.

EXAMPLE 6 A clear vehicle is prepared from part pentaerythritoltriacrylate, /s part hydroxyethyl acrylate, and /3 the adduct formed byreacting one mol of toluenediisocyanate with 2 mols of hydroxyethylacrylate.

The curing procedure is carried out in the same manner described inExample 1. Without the incorporation of any sensitizers no curing(hardening) of the coated film (0.5 mil) is observed even with repeatedexposures to the U.V.

EXAMPLE 7 Into each of the clear vehicles of Examples 1 and 6 there isincorporated by weight of zinc oxide. The now pigment vehicles aresensitized individually by 2% of the chlorosulfonated naphthyl andphenanthryl ketones of the preceding examples. Irradiated in the samemanner as described in Example 1 the pigmented films cure to tack-freestate at line speed of 100 feet per minute.

EXAMPLE 8 In the clear vehicles of Examples 1 and 6 there isincorporated 20% by weight of titanium dioxide (anatasc). The pigmentedvehicles are spread in 0.4 mil thick films on aluminum panels. Alsoreduced to comparably thin films are the pigmented vehicles in twoparts. One has 1-Chloromethyl,6-chlorosulfonyl-naphthyl-Z phenyl ketoneas a sensitizer.

0n exposure to the apparatus described in Example 1 the only films tocure tack-free are those which contain the sensitizer of the invention.By comparison l-chloromethyl naphthalene, as well known sensitizer, isincorporated at 2% into the same pigmented vehicle. No hard cure isobserved at multiple passages of the coated panel at 100 feet perminute.

EXAMPLE 9 A polyester vehicle is prepared from 3 mol phthalic anhydride,3 mol maleic anhydride, 6.8 mol propylene glycol and cooked to an acidnumber of about 30. Styrene is added until 70 n.v. (non-volatiles) isattained. Into the above clear polyester vehicle 2% by weight ofl-chlorosulfonyl anthracyl-9, phenyl ketone. Exposure of panels coatedto 0.5 mil thick to irradiation at line speed of 100 feet per minutegives complete and tack-free cure.

EXAM PLE 1 O A polyester vehicle is prepared from 3 mol maleicanhydride, 3 mol phthalic anhydride, 1 mol propylene glycol, and 6 molpropylene oxide and cooked to an acid number of about after whichhydroxyethylacrylate is added to constitute by weight of the entirevehicle.

Into the above vehicle 2% by weight of 2-chlorosulfonyl phenanthryl-3phenyl ketone is incorporated, followed by applying the vehicle to testpanels as earlier described. subjecting the coated panels to theradiation emitted by the apparatus of Example 1, at line speed'of 100feet per minute produces tack-free, scratch resistant films. Withoutsaid sensitizer the film is wet and tacky even after repeated exposuresto radiation.

EXAMPLE 1 1 A vehicle comprising pentacrythritol tri-acrylate issensitized by 2% S-chlorosulfonyl naphthyl-l phenyl ketone.Substantially the same excellent cure is obtained for 0.4 mil thickfilms at both line speeds of 100 and 200 feet per minute.

8 EXAMPLE 12 The same vehicle of Example 11 is sensitized with 2%1-bromomethyl-6 chlorosulfonyl naphthyl-2 phenyl ketone with the resultsbeing substantially comparable when the same procedure is followed. I

EXAMPLE 13 A clear vehicle is prepared from /2 phenylcellulose acrylateand /2 pentaerythritol triacrylate. 2% of chlorosulfonated phenanthrenephenyl ketones is incorporated into said vehicle which is applied to atest panel as a film of about 1 mil thick. The ketones represent amixture of monochlorosulfonated material wherein the substitution is atthe 2, 6, 7 or 8 position. Following the irradiation procedure describedin the preceding examples the film cures to a tack-free state at a linespeed of feet per minute.

EXAMPLE 14 A vehicle is prepared from /3 pentaerythritol triacrylate, /5Z-diacrylate. Also incorporated into said vehicle is sufficient titania(rutile) to make up a paint with a pigment to vehicle ratio of 0.8 to1.0. Into said paint there is incorporated 2% by weight, based onvehicle, S-chlorosulfonyl, 8-bromomethyl naphthyl-Z phenyl ketone and0.3% by weight, based on the vehicle, of Michler ketone. The sensitizedpaint is applied in films of about 0.4 mil thick and irradiated in thesame manner described earlier. The paint cures to a tack-free state atline speed of 200 feet per minute.

EXAMPLE 15 The vehicle described in Example 14 is prepared again tocontain 3% by weight iron black (ferric oxide) making the now coloredvehicle suitable as a printing ink. The colored vehicle is applied in afilm of about 0.3 mil thick which is then subjected to the apparatussubstrate described at 100 feet per minute. The cure is full andcomplete; no smudging is observed.

EXAMPLE l6 Into a vehicle comprising acrylated soybean oil (availablecommercially from Union Carbide Corporation, New York, N.Y. as FlexolPlasticizer EPO) is incorporated a 2% 4-methoxy, S-chlorohulfonylZ-naphthyl methyl kotone. The sensitized vehicle is applied to a heatsensitive plastics substrate (high density polyethylene) in a thin filmof about 0.6 mil thick. The coated plastics substrate is then subjectedto the curing procedure described above at 100 feet per minute. Thecoated film shows full cure and the substrate shows no distortion.

What is claimed is:

1. In a process for polymerizing an ethylenically un saturatedphotopolymerizable vehicle in which a pigment is dispersed to form apigmented composition, by exposure to U.V. radiation, the improvementwhich comprises incorporating into said vehicle about 0.5-5% by Weightof a carbonylated polynuclear sulfonyl chloride, said pigment being fromabout 20% to about 50% of said composition.

2. The process of claim 1 wherein said sulfonyl chloride is representedby the general formula:

Wherein R is hydrogen, alkyl (C ),.ot -haloa1kyl (C phenyl andsubstituted phenyl wherein the substituent is alkyl, alkoxy,ot-haloalkyl or chlorosulfonyl, polynuclear aromatic radical, R and Rrepresent hydrogen, one or more fused rings, alkyl (C and a-haloalkyl,and n is a number of at least 1.

3. The process of claim 2 further characterized by said sulfonylchloride wherein said R is phenyl and n is 1.

4. The process of claim 2 further characterized by said sulfonylchloride wherein R is phenyl, R is hydrogen and R is a fused ring.

5. The process of claim 2 further characterized by said sulfonylchloride wherein said R is alkyl (C R is a-haloalkyl (C and R ishydrogen.

6. The process of claim 2 further characterized by said sulfonylchloride wherein R is alkyl (C R is alkoxy and R is hydrogen.

7. The process of claim 2 further characterized by said sulfonylchloride wherein R is phenyl, R is a-haloalkyl (C and R is a fused ring.

References Cited UNITED STATES PATENTS 3,702,812 11/1972 McGinnis s204159.24

10 2,579,095 12/1951 Sachs et al. 204159.24 3,113,024 12/1963 Sprague etal. 9685 US. Cl. X.R.

96-115 P; l1793.31, 142 R, 132 R, 138.0 R, 143 A; 204159.14, 159.16,159.18, 159.23; 26025 B, 39 P, 39 M, 395 SB, 41 A, 41 B, 41 C, 41 AB,77.5 CR, 80.75, 80.81, 86.1 E, 851, 856

